Terminating NSTask with NSFileHandle set for standard output

Question

I have a batch of code that creates and runs an NSTask instance. Before running I set, for the standard output of the task, a NSFileHandle witch writes directly to a file I have created.

Sometimes the NSTask is terminated by code (by sending the terminate command) before it completes, sometimes it completes without any outside termination.

When the NSTask completes successfully, the file that I had setup to have the output written to is exaclty as it should be: full of text. However, when I terminate the task in my code, the file has nothing, even though I know for a fact that the NSTask is generating output.

Here's my code:

// Create task
task = [NSTask new];
[task setLaunchPath: @"..."];
[task setArguments: [NSArray arrayWithObjects: ..., nil]];

// Create output file
NSString* path = @"...";
[[NSFileManager defaultManager] createFileAtPath: path contents: nil attributes: nil];

// Create output file handle
NSFileHandle* outputFile = [NSFileHandle fileHandleForWritingAtPath: path];
[task setStandardOutput: outputFile];

[task launch];
// Etc...

I thought that this method would write data to a file as it is generated by the command. And if that's true, then even when the command is forcefully terminated the file should have some info. So why doesn't it?

Just in case I'm mistaken and this doesn't save the output as it is generated, can you point me to a method that does that?